Disclosed herein are mixed polycycloaliphatic amines (MPCA) and alkylates thereof (MPCA alkylates), methods for making mixed polycycloaliphatic MPCA amines and MPCA alkylates thereof, as well as polymeric compositions, such as spray-applied polyurea coating compositions, comprising said mixed MPCA and MPCA alkylates.
The term “polymeric compositions”, as used herein, describes compositions comprising 2 or more repeating units. Specific examples of polymeric compositions include, but are not limited to, polyureas, polyurethanes, and urea/urethane hybrid elastomer or coating compositions. Certain polymeric compositions such as polyurea elastomers are rapid cure coatings that have gel times that can be as short as 2-3 seconds. Because of its rapid cure speed, these polyurea coatings can be applied over a broad range of temperatures, are relatively moisture insensitive, and can be used on a wide variety of substrates. In addition to its application benefits, the fast cure speed may allows users and facility owners to return areas to service much faster than with other coatings systems, saving time and money for both the contractors and owners. These benefits, among others, have all led to significant growth in the polyurea industry over the last two decades.
One problem in the industry has been a lack of standardization in terminology; recent attempts to standardize the terminology include more or less arbitrary definitions of “pure polyurea”, hybrid “polyurea-polyurethane” and “polyurethane” coatings. The impetus behind the attempted standardization is the effect of cure speed and reactivity on both final properties of the cured system as well as the sensitivity of the system to moisture during the spray application process. These delineations focus on the chemistry of the reaction process (as opposed to the chemistry in the manufacture of the components), where the cure speed and potential moisture sensitivity issues arise.
There are many examples of polyurea compositions in both the patent and scientific literature as well as many commercial systems that uses these coatings. Polyurea coatings can be formed by reacting an isocyanate component with an isocyanate reactive component such as, for example a resin blend. The isocyanate component may be generally comprised of a monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer, prepolymer, or combinations thereof. The prepolymer or quasi-prepolymer can be made of an amine-terminated polymer resin, a hydroxyl-terminated polymer resin, or combinations thereof. The isocyanate reactive component or resin blend may be generally comprised of amine-terminated polymer resins, amine-terminated curing agents, hydroxyl-terminated polymer resins, hydroxyl-terminated curing agents, and combinations thereof. The term “curing agent” as used herein describes a compound or mixture of compounds that is added to a polymeric composition to promote or control the curing reaction. In certain systems, the term “curing agent” may also describe chain extenders, curatives, or cross-linkers. The resin blend may also include additives or other components that may not necessarily react with the isocyanate contained therein as well as, in certain systems, catalysts.
While the compositions of these polyurea coatings vary, the isocyanate component within the composition may be generally divided into two broad classes: aromatic and aliphatic. The systems defined as aromatic may use an aromatic polyisocyanate, such as 4,4′-methylene bis isocyanto benzene (MDI), and isomers and adducts thereof. The MDI adducts referred to in both the patent and scientific literature include MDI prepolymers, quasi-prepolymers (which have a mixture of prepolymer and high free MDI monomer level and may be prepared in-situ) and mixtures of MDI prepolymers and quasiprepolymers with other MDI monomer streams. MDI adducts are sometimes prepared using an MDI monomer with a high 2,4′-MDI isomer level to reduce the reactivity and increase the pot life. For spray applied applications, the later property may be referred to as gel time and/or tack-free time. The composition may also employ one or more additional aromatic components such as, for example, the following curing agents, diethyl-toluenediamine (DETDA) or dithiomethyl-toluenediamine (ETHACURE® E300).
When the isocyanate component in the composition is aliphatic, the curing agents that are used as the isocyanate reactive component are generally also aliphatic in nature. Examples of aliphatic curing agents include, but are not limited to, dialkyl-methylene bis cyclohexylamine (which are marketed under the brandname CLEAR LINK®) or the aspartic ester products such as Desmophen® from Bayer Material Science LLC. The remaining ingredients within the polymeric composition, which can be added to either or both the isocyanate and resin blend components and can be aromatic or aliphatic in nature, may include any number of additional components. Examples of additional ingredients in the polymeric composition may include for, example, a polyalkylene oxide (i.e., polypropylene oxide) reacted into the polyisocyanate component to provide a quasi-prepolymer and one or more amine-terminated polypropylene oxides of functionality 2.0 or higher, such as for example, the JEFFAMINE® brand of curing agents.
Typical applications for polyurea compositions may include, for example, bedliners for pick-up trucks, pipe or pipeline coatings and linings, bridge coatings, joint fill and caulk, tank coatings and linings to contain chemical and industrial liquids, marine coatings, roof coatings, waste water treatment linings, manhole and sewer linings, as well as a number of additional applications falling under the general category of “protective coating” or liner. The polyurea composition may be applied as sheets, fibers, foams, adhesives, coatings, elastomers, or other methods. Depending upon its end-use and its application, it is desirable that the polyurea composition exhibits at least one of the following properties: corrosion resistance, abrasion resistance, ease of application, durability, fast cure time, adherence, high tensile strength, high elongation, moisture insensitivity, flexibility, and combinations thereof. Depending upon the end-use, it is also desirable that the polymeric composition exhibit stability upon exposure to a variety of aggressive environments such as, for example, acids, bases, hydrocarbons, fuels, oxygenates, etc.
One of the more desired properties for polyurea compositions is improved chemical resistance. For example, U.S. Publ. No. 2006/0058491 describes a polyurethane-polyurea polymer having a polyisocyanate component and an isocyanate-reactive component that includes at least one organic compound having a mercaptan functional moiety such as a polysulfide. U.S. Pat. No. 6,797,789 describes phenolic/polyurea co-polymers that contain phenolic resins for improved chemical resistance performance.
There is a recognized need for a new family of curing agents which provide the end-user a tool to specifically tailor a wide-variety of cure-profiles and which generally improve the overall formulating latitude of polymeric coating. Further, there may be a need in the art to provide a family of curing agents that may provide improved chemical resistance.